Drive for cinematographic films



Jan. 22, 1935. I A. v. c. DEBRIE 1,938,981

DRIVE FOR CINEMATOGRAPHIC FILMS Filed: Dec. 22, 1933 Patented Jan. 22,1935 UNITED STATES PATENT OFFICE Application December 22, 1933, SerialNo. 703,650 In France February 9, 1933 1 Claim.

In all cinematographic apparatuses such as cameras, projectors, etc. thefilms are generally held in contact with the driving feed drums orsprocket wheels by means of movable presser rolls, adapted to be movedaway from the toothwork of the feed drumsay through a pivotal motion.Now this universally known arrangement is not without showing seriousdrawbacks: On one hand in effect it is cumbersome and costly and on theother hand it makes the loading of the apparatus always long andfastidious.

My invention lras for its object an arrangement which removes thesedrawbacks by omitting the usual presser rolls. It consists in holdingthe film in contact with the feed drum solely through the naturalelasticity of the film, the arrangement being such that the forces whichurge the film against the toothwork oi the drum are greater than thosewhich have a tendency to make it disengage it. In certain cases, thisresult may be achieved solely by giving the feed drum a suitable sizeand providing proper directions for the film when it engages and leavesthe drum. However it will be more generally necessary to resort toguiding parts and/or stops which prevent the film from disengaging thedrum without these parts or stops ever pressing the film positivelyagainst the toothwork, so as to allow the free placing of the filmagainst the toothwork. This part or stop may be of any suitable kind: Arectilinear or incurved channel, a set of guiding rollers, etc.

I have shown two forms of execution of my invention by way of example inaccompanying drawing wherein:

Fig. 1 is an elevational view ofa first form of execution,

Figs. 2 and 3 relate to a secondform of execution, Fig. 2 being a sideview and Fig. 3 a cross-section along line AB of Fig. 2.

In the form of execution shown in Fig. 1, the film moves over the feed'drum 2 in the direction of the arrow 3. In order to allow the naturalelasticity of the film to ensure the contact between it and the drum, Idispose in front of the feed drum 2 a roll 4 acting as a stop andprovided with flanges such as 5. This roll is freely rotatable aroundits axis 6. Behind the feed drum 2, I dispose another roll '7 acting asa stop provided with flanges such as 8 and also i'reely rotatable aroundits axis 9. The film 1 passes on one hand between the roll 4 and thefeed drum 2 and. on the other between the drum 2 and the roll 'I, thispassage being however completely free without the rolls pressing thefilm positively ot the exposure gate.

It may sometimes be necessary to provide, as

shown for instance in Fig. 1, for the part of the' apparatus disposedabove the feed drum, in addition to the rolls 4 and 7, a further rollsuch as 10 which ensures in a perfect manner the desired guidance of thefilm, while reducing to a minimum the frictional resistances.

It is apparent that, by reason of the interval existing between therolls 4 and 7 and the feed drum 2, it is very easy to load the apparatuswithout any further manipulation.

In the form of execution illustrated in Figures 2 and 3, the film 11, asit passes out of the magazine-box 12, is driven by the feed roll 13 andthen after it has made a loop 14, it enters the channel Around the feeddrum 13 and concentrically with reference thereto, there is arranged anarcuate channel 16 serving as a stop and extending over part of theperiphery of the feed drum. It should be well understood that the filmis held against the drum 13 through the action of its own elasticity atthe loop 14 and of the tension of the strand 11, the channel 16 onlypreventing the film from falling in case the film strand or side 11 wereto slacken to an abnormal extent. In the form of execution shown, thefeed drum has a single toothwork'l'l; the transverse cross-section (Fig.3) of the channel 16 has the shape of a U the leg of which on thetoothwork side is exactly adjacent to the flange of the feed drum, whilethe other leg stops at a certain distance from the latter so as to forman arcuate aperture 18 at the periphery of the drum. Under theseconditions, it is easy to introduce the film laterally through theaperture 18 until it abuts through its opposite edge against the firstleg of the U. The perforations will engage then automatically thetoothwork 1'7. The width of the aperture 18 and the distance separatingthe'bottom of the channel from the periphery oi' the drum aresufliciently large to allow the easy introduction of the film.

It is obvious that the above described ex' amples have been given onlyby way of indication and that it is possible in each particular case toresort to the most suitable arrangement of rollers, incurved channels,rectilinear channels, and the like guides or abutments- What I claim is:

In a driving device for cinematographic apparatus a driving sprocketdrum provided with a single range of sprockets, a guide for the fllm 5so disposed that the film is yieldingly applied against the drum, afixed shield covering at a distance the part of the drum upon which thefilm is engaged, said shield having in cross section the shape of a Uone branch of which is much longer than the other; the'longest branchextending alongthe flange of the drum which is the nearest to the rangeof sprockets, the r shortest branch ending near the outer surface of thedrum on the side opposite to the sprockets, and leaving between saidsurface and its own edge a narrow space just large enough to allow thefilm to be engaged on the sprocket drum.

ANDRE LEON VICTOR -DEBRIE.

